Convert M4A to MP3

How to Convert to MP3

1. 1

   Add your M4A or M4B files

   Up to 200 MB each, twenty at a time. Files with a .mp4 or .aac extension containing audio work too.

2. 2

   Choose a bitrate

   192 kbps is a safe match for most M4A sources. Voice memos are fine at 96 or below.

3. 3

   Click Convert and download

   Artist, title, album and the embedded cover come across with the file.

M4A is a container, not a codec

This trips people up constantly. An .m4a file is an MP4 container, the same box format used for video, carrying an audio track that is almost always AAC and occasionally Apple Lossless. That is why the same file sometimes arrives named .mp4, .m4b or even .aac, and why software that claims not to support M4A will happily open the identical bytes under a different name. This page reads the container rather than the extension, so all of those land in the right place. M4B is the audiobook variant: the same container with a flag that tells players to remember your position.

Converting from AAC means a second generation of loss

The audio inside an M4A has already been compressed once. Converting to MP3 decodes it back to samples and compresses it again with a different algorithm that makes different decisions about what to discard. The result is slightly worse than the source, always, and no bitrate setting avoids that; it is inherent to going between two lossy formats. What a sensible bitrate does is make the second loss small enough not to matter: at 192 kbps or above, the difference from a typical 128 kbps M4A is not something you will pick out. Choosing 320 kbps does not recover anything; it just stores the same sound in a larger file. If the file will only ever be played on something that already reads M4A, the best conversion is no conversion.

Voice memos and audiobooks

Recordings from an iPhone arrive as M4A at a low bitrate already, usually mono and around 32 kbps for Voice Memos. Converting those at 192 kbps wastes space on information that was never there; 64 or 96 kbps produces a file of a sensible size that sounds identical to the source. Audiobooks are the other common case: an M4B is often ten or twenty hours in a single file, and the conversion keeps it as one long MP3. The chapter marks that M4B can carry do not exist in MP3 and are lost in the conversion, which matters if you rely on them to find your place.

Tags and artwork survive

M4A files from iTunes and the Music app carry a full set of metadata and usually an embedded cover. All of it is copied into the MP3, with tags written as ID3v2.3, the version Windows Explorer and car stereos read reliably, and the cover carried across as an attached picture. Both can be switched off if you would rather have a completely clean file.

Frequently asked questions